I started the install as usual and then hit the prerequisite screen with a nice big red cross.
No problem I thought, it's just missing VS Shell so I clicked the link to run the install.
However, it then clicked that I shouldn't need to install that as I've had the 2010 Authoring Console on here before and that had the same requirements. Never mind, the install was already complete before I could think twice.
However, clicking "Check prerequisites again" did nothing.
OK... Try closing and restarting. Still nothing.
Ermm.. How about a reboot? Nope, zip.
Now normally I would go through and systematically uninstall Visual Studio Shell 2008 and related items to try and create a nice clean state and try again, however when I saw what was lurking on my system I decided I might need another approach.
Picking up on an answer Anders Asp gave on this forum thread I thought I'd give it a try.
Locate the Authoring_PrerequisiteInputFile.xml in the Setup\en folder (or substitute the language) in the folder where you extracted the Authoring Tool setup files.
Open the file in notepad or XML editor and find the section starting with <Check Order = "03"> and delete that line and everything down to and including the next </Check>
Do not delete the </Prerequisites> line.
Save the changes and then run the installer again. This time when it performs the prerequisites check it should only check for memory and CPU speed.
This let me skip the check that wasn't working for some reason and install the Authoring Tool, which so far opens fine and appears to be functioning ok too.
As always, use this with your own judgement, I dare say it's not a Microsoft supported method and if possible, try uninstalling VS related components and reboot/reinstall them first.
Also, just as a side note, since I always like to automate as much as possible and for packaging/deployment via Configuration Manager I used the following command line once I had verified the install would work to install the Authoring Tool silently.
Setup.exe /install /CustomerExperienceImprovementProgram:Yes /EnableErrorReporting:Yes /silent /AcceptEula /RegisteredOwner:Steve Beaumont /RegisteredOrganization:Trustmarque
No progress bars can be seen, but task manager does show it's running.
And that leaves me with one new shiny 2012 Authoring Tool to play with...